When Sciatica Isn’t From the Spine: A Case of Deep Gluteal Syndrome Linked to an Enlarged Piriformis Muscle

Chronic sciatica is usually blamed on the spine, but a newly published case report reminds clinicians that the nerve can also be trapped much lower, in the crowded muscular corridor of the buttock. Writing in the open-access journal Case Reports in Rheumatology, a rheumatology team describes a middle-aged man whose disabling leg pain was traced not to a herniated disc but to a hypertrophied piriformis muscle compressing the sciatic nerve deep in the gluteal region. The case, published as part of a broader discussion of deep gluteal syndrome, illustrates how a condition once dismissed as rare and controversial can be identified with careful clinical testing and targeted imaging.

The patient, a long-distance lorry driver, arrived at the rheumatology department carrying a referral for a supervised exercise reconditioning programme for chronic low back pain. He had endured back discomfort for a year, but over the previous six months a far more troubling symptom had emerged: burning pain radiating down one leg, consistent with sciatica, that had grown steadily worse despite treatment with non-steroidal anti-inflammatory drugs. The pain threatened his livelihood, since prolonged driving is exactly the posture that aggravates entrapment of the sciatic nerve in the deep gluteal space.

What made his presentation unusual was the pattern of tenderness. Rather than the diffuse back pain typical of disc disease, he had exquisite point tenderness in the buttock, and the pain radiated down the leg in a distribution matching the sciatic nerve. On examination, his surgeons found no neurological deficit: muscle strength, reflexes and sensation were all intact. That combination, pain without weakness, is a hallmark of nerve entrapment rather than nerve compression by disc material, and it prompted the team to look beyond the lumbar spine.

To test the hypothesis of deep gluteal syndrome, the clinicians performed a battery of provocative manoeuvres designed to stress the piriformis and neighbouring structures. The flexion-adduction-internal rotation test, in which the hip is pushed across the body while internally rotated, reproduced the patient’s exact pain. The seated piriformis stretch test and the active hip flexion, adduction and internal rotation manoeuvre were also positive. These tests, drawn from the sports medicine literature, have increasingly been promoted as a practical bedside toolkit for distinguishing deep gluteal syndrome from lumbar radiculopathy, and in this patient they pointed decisively toward the buttock rather than the back.

Imaging then settled the question. Computed tomography of the pelvis revealed a striking asymmetry: the left piriformis muscle, measured on the original dataset, had a cross-sectional area roughly fifty per cent larger than the right. No disc herniation, spinal stenosis or nerve-root conflict was present on lumbar imaging, and blood tests showed no inflammatory activity. The muscle enlargement, in the absence of any other explanation, was judged to be the source of the nerve compression, a mechanism consistent with the anatomical studies that first described how a hypertrophied piriformis can narrow the subpiriformis space through which the sciatic nerve passes.

Deep gluteal syndrome, sometimes called piriformis syndrome in its older and narrower usage, has undergone a substantial conceptual expansion in recent years. Review articles now emphasise that the sciatic nerve can be entrapped at multiple sites within the deep gluteal space, including the piriformis muscle, the gemelli and obturator internus, the hamstring tendons and fibrous bands near the ischial tuberosity. Trauma, prolonged sitting, hip surgery and anatomical variants such as a split sciatic nerve or an anomalous piriformis have all been implicated. The authors argue that the term piriformis syndrome is too restrictive, since the piriformis is only one of several potential culprits, and that deep gluteal syndrome better reflects the true anatomy of the region.

Diagnosing the condition remains difficult, and the case report is candid about the limitations of current tools. Magnetic resonance imaging can reveal muscle asymmetry and anatomical variants, but no single measurement is definitive, and ultrasound is emerging as a dynamic alternative that can visualise the sciatic nerve during hip movement. Electrodiagnostic studies may support the diagnosis when they show prolonged H-reflex latency with normal conduction elsewhere, but they are not universally abnormal. In practice, the diagnosis is often clinical, resting on a characteristic history of buttock pain radiating down the leg, aggravated by sitting and by hip rotation, together with positive provocative tests and the exclusion of lumbar pathology.

Treatment in this case began conservatively, with analgesia and physiotherapy, but the pain proved refractory. The team therefore proceeded to a CT-guided injection of corticosteroid and local anaesthetic directly into the belly of the hypertrophied piriformis muscle, a technique that allows the needle to be placed with millimetre precision while avoiding the sciatic nerve and the gluteal vessels. The result was dramatic: the patient reported complete relief of his sciatica shortly after the injection, and at follow-up the improvement was sustained, allowing him to resume work and daily activities without restriction.

The authors place this outcome in the context of a growing evidence base for injection therapy in deep gluteal syndrome. Systematic reviews report that local anaesthetic, corticosteroid, botulinum toxin and even platelet-rich plasma have all been used with benefit, although the quality of the underlying studies varies and randomised trials remain scarce. Botulinum toxin, which relaxes the muscle rather than simply suppressing inflammation, has attracted particular interest, and some retrospective series suggest it produces longer-lasting relief than corticosteroid alone. Open surgical release of the piriformis, once the mainstay of treatment, is now reserved for refractory cases, since endoscopic and image-guided techniques offer comparable results with far less morbidity.

The case carries a broader message for clinicians and for patients with unexplained leg pain. Sciatica is a symptom, not a diagnosis, and the lumbar spine is only one of the structures capable of generating it. When back pain fails to explain the clinical picture, when neurological examination is normal, and when provocative manoeuvres of the hip reproduce the pain, the deep gluteal space deserves systematic attention. The authors conclude that deep gluteal syndrome should be considered in every patient with sciatica of uncertain origin, because a diagnosis that is missed condemns the patient to months of ineffective treatment, while a diagnosis that is made can be relieved with a single, precisely targeted injection.

Subject of Research: Deep gluteal syndrome caused by piriformis muscle hypertrophy entrapping the sciatic nerve

Article Title: Deep Gluteal Syndrome and Persistent Sciatica in a Patient With Unilateral Piriformis Muscle Hypertrophy: A Case Report

Article References: Ghani, N. (2026). Deep Gluteal Syndrome and Persistent Sciatica in a Patient With Unilateral Piriformis Muscle Hypertrophy: A Case Report. Clinical Case Reports, 14(10), Article e73730. https://doi.org/10.1002/ccr3.73730

Image Credits: AI Generated

DOI: 10.1002/ccr3.73730

Keywords: deep gluteal syndrome, piriformis syndrome, sciatic nerve entrapment, sciatica, CT-guided injection, case report, Deep, Gluteal, Syndrome, Persistent, Patient, Unilateral